On Wed, 4 May 2016 05:35:41 -0700 (PDT), David
wrote:

Or should I place stones or bits of broken crockery over the hole first? It seems to me that placing solid items over the hole will obstruct drainage.

I've tried several systems, including

(a) doing nothing
(b) adding large stones, kindly left by builders in case I needed them
(c) adding terracotta pot fragments
(d) adding terracotta fragments plus grit.

With all these methods, silt from the JI compost I use would
eventually wash through and block the hole, it just took varying
lengths of time. So now I use option d AND I put all my pots on pot
stands. It helps when the window cleaner comes anyway.

Them feety things are hopeless, I was forever knocking pots over when
I tried them.

It's a good idea to use mesh or fleece, though: I'm definitely going
to give that a try. Can't believe I never thought of it. But I'll
still use a pot stand just in case.
--
Bob Moore
http://bobmoore.mvps.org/